Bare Sudoku is a free Sudoku game that runs directly in a web browser. It requires no account, displays no advertisements, and includes no tracking or third-party scripts. The page can be played immediately after opening, and after the first visit it is stored by the browser, allowing offline play. The same functionality is available as a native Android app, which is distributed as a signed APK from GitHub instead of through a store. The game offers five difficulty levels: Easy, Medium, Hard, Expert, and Master. Every puzzle is generated with exactly one solution and is designed to be solved through logic alone. Features include notes, undo, erase, and fill all notes with one tap, as well as highlights for rows, columns, boxes, and identical digits. Hints explain the solving technique used for the next cell, ranging from singles and pairs to X-Wing, Skyscraper, Unique Rectangle, and at Master level, chains and forcing nets. Additional options include mistake marking, automatic save, dark mode, keyboard support, and landscape layout. The interface is available in 59 languages, each on its own page. Typical use cases include casual puzzle solving, learning Sudoku techniques through guided hints, and playing offline. The website provides separate guides that explain the rules and every solving technique used by the hints, each with a real example. The Android app is about 54 KB, requires Android 8 or newer, has no permissions, and never accesses the internet. The project is open source under the MIT license. Privacy is limited: the site keeps only anonymous counters such as page opens and games started or finished, aggregated by level, language, device type, and referring site. No IP addresses, cookies, or accounts are used, and the current game is saved only in the browser's local storage.